<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title></title>
</head>

<body>
<script>

var r = new RegExp("a"+ s + "b","g");	// 动态创建正则表达式
var r = /"a"+ s + "b"/g; 				// 错误的用法


</script>
</body>
</html>
